/*
 * Copyright (c) 2007, Nathan Sturtevant
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the University of Alberta nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY NATHAN STURTEVANT ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL <copyright holder> BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.googlecode.pathmachine.mm;

/**
 * A SearchNode is a fairly heavy representation of a node used for
 * search within GenericAStar. It makes no assumptions about the
 * underlying implementation. For grid-based worlds, for instance, we
 * can use integer values for the f- and g-costs, if we make diagonals
 * 1.5 and then multiply the value by 2.
 *
 * Using optimized data structures here will speed A* by a factor of
 * two or more.
 * 
 * @author Nathan Sturtevant
 * @author <a href="mailto:eriq.adams@gmail.com">Eriq Muhammad Adams J.</a>
 */
public class SearchNode {

    public double fCost;
    public double gCost;
    public int currNode;
    public int prevNode;

    public SearchNode() {
    }

    public SearchNode(double fCost, double gCost, int currNode, int prevNode) {
        this.fCost = fCost;
        this.gCost = gCost;
        this.currNode = currNode;
        this.prevNode = prevNode;
    }

    public SearchNode(int currNode) {
        this.currNode = currNode;
    }

    /**
     * Compare two search nodes and return true if they are equal
     */
    public boolean equal(SearchNode i2) {
        SearchNode i1 = this;
        return (i1.currNode == i2.currNode);
    }

    /**
     * Compare two search nodes and return true if i2 should be
     * opened before i1.
     */
    public boolean compare(SearchNode i2) {
        SearchNode i1 = this;
        if (FPUtil.fequal(i1.fCost, i2.fCost)) {
            return (FPUtil.fless(i1.gCost, i2.gCost));
        }
        return (FPUtil.fgreater(i1.fCost, i2.fCost));
    }

    /**
     * @return Return a hash-key for the search node.
     */
    public int hash() {
        return this.currNode;
    }
}
